What Is ADEM?

Have you ever heard of ADEM?

Most parents haven’t.

That’s probably good, because although you should be familiar with different things, if you know what it is, then you likely know someone who has been affected by it.

What Is ADEM?

ADEM, an autoimmune disease, is an acronym for Acute Disseminated Encephalomyelitis.

“Acute disseminated encephalomyelitis (ADEM) is characterized by a brief but widespread attack of inflammation in the brain and spinal cord that damages myelin – the protective covering of nerve fibers. ADEM often follows viral or bacterial infections, or less often, vaccination for measles, mumps, or rubella.”

Acute Disseminated Encephalomyelitis Information Page

Children and young adults with ADEM can have:

  • encephalopathy with confusion and irritability
  • hemiplegia – paralysis on one side of the body
  • ataxia – loss of full control of bodily movements leading to an unsteady walk
  • optic neuritis with vision impairment and vision loss
  • myelitis – inflammation in the spinal cord
  • speech impairment
  • hemiparesthesia – numbness on one side of the body and other sensory changes
  • seizures – especially in younger children

These symptoms typically follow a few days of fever, headache, nausea, vomiting, and feeling tired.

And to make the diagnosis, children with these symptoms of ADEM will have “focal or multifocal lesions predominantly involving white matter” on an MRI of their brain.

Fortunately, although ADEM can be life-threatening, there are treatments (steroids) for these kids and usually the outcome is good, with a complete or near complete recovery.

ADEM and Vaccines

Why do some folks associate ADEM with vaccines?

Mostly because some anti-vaccine websites like to try and associate ADEM with vaccines.

“ADEM is usually triggered by a preceding viral infection or immunization.”

Infection and Autoimmunity, Chapter 60

A lot of textbooks still list vaccines as a rare trigger too…

In this 2011 report, the IOM concluded that few health problems are caused by or clearly associated with vaccines.
In this 2012 report, the IOM concluded that few health problems are caused by or clearly associated with vaccines.

It is important to understand that ADEM most commonly occurs after a nondescript (not easily described), natural, viral or bacterial infection.

Interestingly, one of the first cases of ADEM was reported in 1790 – in a 23-year-old women who had just gotten over measles. Like many other serious complications of measles, ADEM is reported to occur after 1 in every 1,000 cases of measles.

What other infections can cause ADEM?

Most of them.

From HHV-6 (causes Roseola) and the coxsackievirus  (hand, foot, and mouth disease) to HIV and Dengue, they are all associated with ADEM. Many bacterial infections too, like Strep, Mycoplasma, and Salmonella.

“Older formulations of rabies vaccine did cause Acute Disseminated Encephalomyelitis (ADEM), but newer formulations of rabies vaccine have not been shown to cause ADEM, and rabies vaccine is not routinely recommended to the general population in the United States. Other vaccines that are currently routinely recommended to the general population in the U.S. have not been shown to cause ADEM.”

Institute for Vaccine Safety on Do Vaccines Cause Acute Disseminated Encephalomyelitis (ADEM)?

So what about vaccines?

Why do some folks still say that ADEM can follow getting vaccinated, especially after the 2012 IOM report on Adverse Effects of Vaccines: Evidence and Causality, found all of the evidence linking ADEM to vaccines “weak,” and in most cases, that the epidemiological evidence was “insufficient or absent to assess an association between” the vaccines and ADEM?

“Post vaccine aetiology was described for 5% of all ADEM cases and several vaccines have been described to be related to this condition. The incidence of ADEM onset ranges from 1/106 to 1/105 and may change between different vaccine formulations. Epidemiological data about this adverse event are still missing; this may be due to the rarity of post vaccine ADEM.”

Pellegrino et al on Acute Disseminated Encephalomyelitis Onset: Evaluation Based on Vaccine Adverse Events Reporting Systems

At most, ADEM is a very rare, 1 in a million type (1/106) vaccine reaction that is mainly published about in case reports and by reviewing VAERS.

Interestingly, no trigger is reported in up to 30% of cases (they don’t recall having a recent infection or getting a vaccine) and an infectious agent (a virus or bacteria) is usually not isolated from these children once they develop symptoms of ADEM.

“Epidemiologic evidence from this study suggests an infectious cause for ADEM. The agent is most likely a difficult-to-diagnose winter/spring respiratory virus.”

Murty et al on Acute Disseminated Encephalomyelitis in Children

Being so rare, it is hard to prove that ADEM absolutely isn’t caused by vaccines, but it does seem clear that many vaccine-preventable diseases might, from measles, mumps, rubella, chicken pox, flu, to hepatitis A.

Want to try and avoid ADEM? Get vaccinated.

What To Know About ADEM and Vaccines

Although vaccines have rarely been thought to cause Acute Disseminated Encephalomyelitis historically, it is very important to keep in mind that the overwhelming majority of cases of ADEM are caused by natural infections, many of which are vaccine preventable.

More About ADEM and Vaccines

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